Search found 1317 matches

by Chr$
Mon May 13, 2024 11:08 pm
Forum: Software & Programming
Topic: 68K/OS "ROM" based disk attempt
Replies: 34
Views: 1521

Re: 68K/OS "ROM" based disk attempt

I'm thinking about what format to use for the resulting microdrive image. QLay's MDV image looks general on the surface, but it's not, it only works because emulators know the image format and that is specific to QDOS (512-byte sectors, etc.). Another issue is that it doesn't explicitly store the m...
by Chr$
Sun Apr 28, 2024 1:57 pm
Forum: Hardware
Topic: Sandy disc interface
Replies: 1
Views: 267

Re: Sandy disc interface

That'll be a parallel printer connection: https://dilwyn.qlforum.co.uk/docs/manuals/sandy.pdf
by Chr$
Fri Apr 26, 2024 9:46 pm
Forum: Hardware
Topic: Announcing the new "Gold Card" - QIMSI Gold
Replies: 45
Views: 4211

Re: Announcing the new "Gold Card" - QIMSI Gold

I had a feeling it would be based on the QIMSI. What else were the space at the top left edge and the unpopulated chip bottom right going to be ;). Nice work, I look forward to having a play.
by Chr$
Thu Apr 25, 2024 9:53 pm
Forum: The Off-Topic Section
Topic: PSU Primary side issue (non QL)
Replies: 14
Views: 1265

Re: PSU Primary side issue (non QL)

Fixed it! Thanks to Pr0f for directing me away from the primary side of the PSU as there was nothing wrong with it! I measured D512 and it had no voltage. Unplugged the next most important board along (the Chassis board II) and the diode showed 5v. Tested again on the EPROM that is on the PSU board ...
by Chr$
Wed Apr 24, 2024 11:52 am
Forum: The Off-Topic Section
Topic: PSU Primary side issue (non QL)
Replies: 14
Views: 1265

Re: PSU Primary side issue (non QL)

Using my crude methods the new thyristors test very similar to the removed part. So I'll fit a new (NOS) one and will then test voltages at various places on the secondary side. What I can also do - as various other boards are plugged into the main PSU board - is remove some/all of them and see if t...
by Chr$
Sun Apr 21, 2024 8:27 pm
Forum: The Off-Topic Section
Topic: PSU Primary side issue (non QL)
Replies: 14
Views: 1265

Re: PSU Primary side issue (non QL)

I ordered a couple. Cheap enough and easy to swap.
by Chr$
Sat Apr 20, 2024 11:42 pm
Forum: The Off-Topic Section
Topic: PSU Primary side issue (non QL)
Replies: 14
Views: 1265

Re: PSU Primary side issue (non QL)

If you have a multimeter with a DC input voltage rating of 500v or higher - you should be able to measure across the main capacitor - on DC voltage range - you should see some 350-400V. You could also check the stripe (cathode) side of the rectifiers on the secondary side - these should give some i...
by Chr$
Sat Apr 20, 2024 5:50 pm
Forum: The Off-Topic Section
Topic: PSU Primary side issue (non QL)
Replies: 14
Views: 1265

Re: PSU Primary side issue (non QL)

My 'scope isn't rated for that high. I wonder if that new big cap is crap.
by Chr$
Sat Apr 20, 2024 5:06 pm
Forum: The Off-Topic Section
Topic: PSU Primary side issue (non QL)
Replies: 14
Views: 1265

Re: PSU Primary side issue (non QL)

I get 320v across the big cap (C395) but from the cap negative to pin 5 of the transformer (the circled test point no.1) the multimeter throws a fit but did briefly show around 11v. Not 400v!

So that seems to confirm that the issue (assuming it's the only issue) is on the primary side?
by Chr$
Sat Apr 20, 2024 4:49 pm
Forum: The Off-Topic Section
Topic: PSU Primary side issue (non QL)
Replies: 14
Views: 1265

Re: PSU Primary side issue (non QL)

Thanks ever so much Pr0f. There is indeed an illustration of what to expect at those circled points: GrundigPrimary2.jpg Before I dig out the oscilloscope, circled no.1 should be approx 400v and it's one of the winding ends (the 5 between 5 and 3). But I assume it should be 400v between circled poin...